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For our current project it would be most useful if the rotation of a selection could make use of feathering.
What i need is for the parts of the image that are not moving to stay connected in a fluid way to the imageparts that are transformed.
to express it visually; it should connect like rubber and not like mist.
The current fade usually does not deliver the best result because the smoothing of the selection of the rotation causes a smudged crossfade (mist).

Strangely enough, this fade starts appearing as a smudge with a rotation of zero degrees (Bug?)
this is a 400pixel diameter circle selection with a smoothvalue of 100, and a transformtoolrotation of zero : white smudge appears even if the rotation is zero?

when you make any rotation there will be a smudge (caused by the fading of the smooth setting of the selection)
this is smooth value 100

I would like to have a way in tvpaint where rotating part of an image can be achieved with a gradual distortion (rubber), instead of a gradual fade.
and also have a larger fade range then 100, so that i t would be possible to do this: this image was achieved using the warpgrid, it has to be done manually and is quite labor intensive as you cannot create a bounding box on selected gridpoints.
This would be an alternative way of achieving what i want,
add an option to manipulate multiple selected gridpoints of the warping grid with the use of a bounding box.

Tornado FX maybe ?

ah i forgot about that one, it is close in a way...but alas... in its current state its is not really usable for our needs.

i used a circle selection for the example but in practice the selection shapes are very random, i want something that allows you to rotate and move a group of pixels while keeping a connection to the pixels outside of the selection.
to maintain the continuity of the shape, preferably such way that you cannot tell afterwards where the edge of the selection was.

The warp grid could be perfect... but its interface is lacking....a lot!
and its not possible to animate.

The tornado twists all of the inside of the selection, maybe if some controls were added to include a range.
Then it could be made to do what i asked above.

Just did a test with the old wrapping grid: It's possible, but a PITA. And you can't reuse it other than in the exact same spot since you can't scale it.

Use the circular GUIDELINE option and set a circle center and size.
Then under optical flow, set fairly fine grid resolution.
Then set size and power of deform brush.
Then test the circle you want.

Note that you can assign a shortcut key to "FX STACK: APPLY" that lets you apply the deformation once for each tap of the shortcut key, to the current frame only.

Then you can use that shortcut key a specific number of times on a sequence of frames to progressively increase/decrease the intensity of distortion.

Note also that you can easily delete the current circular guideline and draw a new one to change the center and size of the circle...

Here's an example which uses multiple circular deforms (also the background has been wrapped and unwrapped)...
sven

I think this is closer to what you want to do?
It's quick and dirty and rather convoluted, combining a keyframer operation with a flow deform operation (the seam doesn't quite match up but it could, given more care...) sven

Thanks Sven Eric and Marcus,
i need it to manipulate part of a drawing element without that part loosing its connection to the rest of the element.

its maybe a convoluted way to express it.
but what i need it for is to make painted strokes line up with a line drawing on a toplayer.
sometimes i only need to adjust a part of the painted stroke.
but when i make a selection with the transform tool i loose the connection with the part i want to remain in place.

all the above is in search of a way to manipulate in such a way that no cracks appear: you can cover the crack a litttle bit with a feather, but its usually not satisfying... it becomes mist like: it should be rubbery, a bit like this: this was done with the warptool, but he warptool is also very limited in its controls.
You cannot rotate a selection of points, you cannot control the arc of the stretch...